I have 5d mk1 and 430 ex 1.
I found somewhat weird thing happening when I set up my body Aperture priority mode and flash in manual mode.
When I put in these setting (body a-mode, flash m-mode), then my shutter speed won't change and stuck at 1/200. (I am trying to lower the shutter speed like 1/50 and do know about high speed sync).. Also, I double checked custom function number 3(Flash sync speed in Av mod) which is 1.(auto) 2. (fixed at 1/200).

I think when I used 580 ex2, I was able to change shutter speed in the same setting but I don't understand why this is not working with 430 ex.

mlbsport wrote:
Omar, thanks for fast reply but like I said in the question, I did change those functions.. but nothing happens...

Oops sorry…didn't read your question thoroughly. I just place my 580 flash on my 5D (in AV priority) and with the flash in manual mode, the shutter speed is fixed at 1/200 regardless of the custom function settings.

mlbsport wrote:
...so I guess it's just not me who has same issue... but the weird thing is that I was able to change shutter speed in same setting with 580 ex2...

It's not just you; my 20D/580EX combo locks at 1/250 (max sync) when the camera is in Av and the flash is in Manual. Custom function 3 should really read "Shutter speed when camera is in Av Mode and flash is in ETTL." (I don't have my 7D or 430EX II with me at the moment, so I can't check that, but if I recall it works the same way.)

My question is, how were you able to change the shutter speed in Av mode when your 580EX II was mounted? (Or do you mean the shutter speed would change by itself?)

BrianO wrote:
It's not just you; my 20D/580EX combo locks at 1/250 (max sync) when the camera is in Av and the flash is in Manual. ...(I don't have my 7D or 430EX II with me at the moment, so I can't check that, but if I recall it works the same way.)

Okay, I've got the 7D and the 430EX II in hand now, and there's a twist:

The 7D has three options for this in the Custom Function: 1) Auto, 2) 1/60 - 1/250, and 3) 1/250 Fixed. When I put my 430EX II in Manual power mode, with the C.Fn. set for 1 all speeds were available, just as in ETTL mode. With the C.Fn. set for 2 the display shows 1/60 in my current dark conditions. With the C.Fn. set for 3 the display shows 1/250.

Next, I tried it with my old 580EX on the 7D. Again, everything worked as the menus said they should, regardless of ETTL or Manual.

So, this doesn't seem to be a flash Mark I versus flash Mark II thing, but an older body versus newer body thing. It's not a problem for me, because when my flash is in Manual I'm almost always also shooting with the camera in Manual; but it is an odd quirk that on the older bodies, Manual flash essentially ignores C.Fn. 3 and locks the shutter at max sync.

Now, it's clear why it is fixed at 1/200...
I was little worried that maybe my flash has defeat because I bought it as used.. but now I don't have to worry about it..
I don't really shoot the flash in Manual and body in Av-mode but it was just weird because I don't see any particular reasons why Canon would blocked the shutter speed...